1. Field of the Invention
The present invention relates to a data communication apparatus, and more particularly to a data communication apparatus to be used with a relaying multi-address transmission (or calling) system.
2. Related Background Art
A facsimile device has been known as one of the apparatus of this type.
In the prior art facsimile device, the relaying multi-address transmission is instructed from a relay requesting station to a relaying station together with image information. The relaying station sequentially sends in the multi-address call mode the received image information in accordance with the instruction of multi-address call from the requesting station. When the information is not normally sent and there exists a non-delivery station, the relaying station sends a relay report to the requesting station to inform it of the existence of the non-delivery station. The relay requesting station checks the non-delivery station based on the relay report, manually designates the non-delivery stations one by one and resend the information to those stations.
In order to solve the above inconvenience, it has been proposed to instruct the multi-address transmission from the relay requesting station to the relaying station so that the relaying multi-address transmission is retried only to the non-delivered stations.
However, the above proposal includes the following drawbacks:
(1) When the status of the communication line from a destination station to the relaying station is bad or the relaying station is down or busy for a long time so that the relaying multi-address transmission is not attained, there is a high possibility of non-delivery even if the relaying multi-address transmission is retried. Thus, the document hardly reaches the destination station through the relaying station.
(2) It is normally considered rare case (one station or so) that the information is not normally sent to the destination station from the relaying station and the information is not delivered to the destination station. Thus, if the relaying multi-address transmission is to be retried, the burden of the relaying station increases, which leads to the rise of the communication cost.
The relaying multi-address transmission is disclosed in U.S. Pat. No. 4,785,355, and U.S. patent applications Ser. No. 442,721 (now U.S. Pat. No. 5,196,843 ) filed on Nov. 29, 1989, U.S. Ser. No. 330,826 filed on Mar. 30, 1989, and U.S. Ser. No. 451,185 filed on Dec. 15, 1989 (now U.S. Pat. No. 5,111,307).
However, none of the proposals has solved the above problems.